Slug A, at top, is slipper-shaped with dark spots on body. Snail B, below, has flatter body and helical shell on middle of back. Black and white art.

Figure 28A–B. Slug (no shell present) (A); snail (helical shell present) (B).

Slug A, at top, is slipper-shaped with dark spots on body. Snail B, below, has flatter body and helical shell on middle of back. Black and white art.

Illustrations by USDA.